1. Field of the Invention
The present invention relates to a stereotactic device of simplified structure that is adaptable to align and precisely orient a variety of medical devices such as differently sized needles, cannulas and guide wires into the human body for procedures such as tumor biopsies, percutaneous discectomies, cyst aspirations and tumor localizations. The device of the present invention is adapted for use in combination with a stereotactic bridge comprised of a span rotatable on its horizontal axis and movably affixed to a C.T. scan table or X-ray table by positioning means. The positioning means allows vertical and horizontal movement of the span relative to said tables. The embodiment of the present invention relating to the combination of stereotactic device and bridge provides enhanced accuracy of placement and orientation of the medical device and avoids deviation during insertion attributable to hand movement. The device is interactive with a C.T. scanner to achieve accurate placement of the oriented medical device. The embodiment of the invention involving the use of the stereotactic bridge allows alignment of medical devices in sagittal orientation with a high degree of accuracy. Verification of positioning using the bridge can be accomplished in a facile manner.
2. Description of the Prior Art
The need for facilitating subcutaneous injections and orienting the insertion of cannulas or needles with precision in surgical procedures has given rise to the development of numerous devices adapted for such purposes.
An early device for facilitating subcutaneous injection is described in U.S. Pat. No. 3,021,842. A locking ball and socket arrangement is disclosed which is used for positioning a needle at a desired angle. To lock the ball in the socket at the preselected angle, the patentee provided a ball-engaging ring that was threaded on the socket.
More recently, after the advent of C.T. scanning, new devices for orienting and inserting cannulas or needles have been developed.
C.T. scanners are commonly used to provide doctors with cross-sectional internal pictures of a patient. Through the use of C.T. scanner technology, physicians are able to accurately place biopsy needles and drainage catheters into preselected areas of the body with a high degree of success.
C.T. scanners are capable of measuring a proposed trajectory for a biopsy needle or drainage catheter to within 0.1 millimeters with respect to depth, and within 0.1 degree with respect to angular orientation.
A hand-held needle guidance device which is suitable to accurately and easily use C.T. generated information to position a biopsy needle or drainage catheter relative to a patient's body is described in U.S. Pat. No. 4,733,661. The described guidance device utilizes a needle support arm hinged at the end of a planar base. The arm is oriented by protractor means also situated at the hinged end of the base. A wing nut arrangement is used to lock the pivoting arm at a predetermined angle relative to the planar base. The planar base is horizontally oriented by a circular bubble level on the base.
In apposition to the simple hand-held guidance device of U.S. Pat. No. 4,733,661, one finds in the art highly complex C.T. scanner guided stereotactic brain surgery devices utilizing skull mounted frames with associated complex positioning instruments. Such instruments, as pointed out in U.S. Pat. No. 4,733,661, are well-known in the art, such art being well referenced in U.S. Pat. No. 4,733,661.
A C.T. scanner guided stereotactic brain surgery instrument described in U.S. Pat. No. 4,350,159 is used to precisely insert an electrode in the brain of a patient for treatment of nervous disorders. The orientation of the inserted electrode at an angle to the plane formed by the frame is achieved utilizing a semicircular rotatable arc mounted on the frame onto which a movable electrode carrier can be locked. A separate protractor is used to orient the electrode carrier. For drilling the hole through which the electrode is inserted, the arc is rotated part of the way.